The Breeding Bird Survey (BBS) is the most reliable source of data for the Brown Thrasher, with good coverage of the species' breeding population, which is concentrated across southern Canada. BBS results indicate that the population exhibited a steady decrease in numbers until about 2000, and then stabilized somewhat at that lower level. At the regional level, the Bird Conservation Regions (BCRs) with reliable trends (displayed below) show varying levels of decline. The Brown Thrasher population in the Boreal Taiga Plains BCR has experienced the largest decrease in abundance (76%), while the population in the Prairie Potholes BCR has shown little overall change since 1970 (though with a slightly negative trend). BBS results from throughout North America show a steady decrease in the continental population similar to that in Canada. The Brown Thrasher population is below the lowest acceptable level relative to its national population goal (see Canada graph below).
Additional information on: Breeding Bird Survey (BBS) - Canadian analysis
